This invention relates to switched reluctance motors, and more particularly to such motors designed for operation at various speeds.
Switched reluctance motors have attracted considerable attention over the past ten to fifteen years, primarily due to the simplicity of their construction and high power densities (ratio between output power and weight). These motors are doubly salient motors, having teeth on both the stator and the rotor, with phase windings only on the stator poles.
Except for very small (below 50 watt) motors, most switched reluctance motors are designed to operate below 2000 RPM because the core losses in switched reluctance motors are several times larger than in conventional machines of the same size. For that reason, conventional wisdom is that switched reluctance motors are best suited for low speed applications. Of course motors for certain applications (such as washer motors) are required to operate at much higher speeds.
Heretofore, switched reluctance motors operating over a wide speed range suffered from several disadvantages. The power factor of such motors was generally poor. These factors have heretofore made switched reluctance motors an undesirable choice for operation over a wide speed range.